Import meshes, scenes and texture failure

[Modos]

Hello forum!

I'm still new to babylon, but I want to go overboard and create a first-person-shooter with an AI and case-based reasoning (maybe with JADE and myCBR).
But that's just the intro, now to the important part:

For this goal I don't want to create everything by myself. I thought I could easily import a character model and a scene that fits as environment for a FPS.
For test purposes I tried to import some meshes - skull.babylon and dude.babylon:
https://www.babylonjs-playground.com/#JUKXQD (skull.babylon)
https://can't find dude.babylon anymore

I did it by searching in the example tab, opening the playground and downloading via Zip-Button.
Is there another way to look for scenes and meshes to import (except demos)? And maybe a better way to save them.
 

Bla bla bla here is my problem:

As you can see in the picture, the dude-character doesn't has his texture. 
That happens to me for most textures I want to put on meshes. How can I add a texture properly to a mesh? Or why are some textures not shown right?
Another Example that isn't working with some links:

 

var ground = new BABYLON.Mesh.CreateGround("ground", 50, 50, 1, scene);
			ground.material = new BABYLON.StandardMaterial("groundMat", scene);
			ground.material.diffuseTexture = new BABYLON.Texture("https://previews.123rf.com/images/mansum007/mansum0071511/mansum007151100626/47766920-hei%C3%9Fe-lava-muster-illustration-hintergrund.jpg");

This is the primary the code I downloaded, i just repeated the import function for dude.babylon.
https://playground.babylonjs.com/#VKVHP6

 

As always, i thank you in advance for your solutions or advices.
 

 

[DylanD]

Hey this is the old forums...

Try reposting to the new ones https://forum.babylonjs.com/